Coming back to gravity, let us note the analogies between the low-energy (relative to their respective unitary cutoffs \(\Lambda _U\) ) \(\pi \pi \)  and graviton-graviton interactions. Both stems from derivative couplings and its treatment is within the EFT paradigm, cf. Eq. (). Then, a natural question that emerges is whether there is an analogous relatively low-lying resonance in graviton-graviton scattering, since one also expects there to have attractive interactions. This question was addressed in Refs. [1]}, [2]} in the affirmative sense, and the resulting resonance was called the graviball and its pole position \(s_P\) . Here we are going to review on this finding, the method developed for unitarizing infinite-range interactions, and the illustration of the latter when applied to nonrelativistic Coulomb interactions, whose solution is exactly known [3]}.
